


Crawling Flesh

by detri



Category: Fate/Zero, Fate/stay night & Related Fandoms
Genre: Anal Sex, M/M, Masochism, Masturbation, Rough Sex, Semi-Public Sex, Sex Pollen, or sex worms anyway, typical Matou family suffering, warning contains wORMS
Language: English
Status: Completed
Published: 2018-08-18
Updated: 2018-08-18
Packaged: 2019-06-29 09:02:42
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,493
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/15726222
Author URL: https://archiveofourown.org/users/detri/pseuds/detri
Summary: He could barely think anymore. When he wasn't trying to get a few fleeting moments of rest and respite, or frantically biting and scoring his skin to distract from the agony of the worms, he was trying to get his body calmed down, just trying to have any amount of time when he wasn't torn between physical and sexual torment.





	Crawling Flesh

**Author's Note:**

> It's bullshit that Crest Worms only cause Magical Horniness in women so here, I made Kariya suffer even more

Kariya was theoretically free to use the Matou house as a base of operations, but most nights he found himself sleeping on the streets.

Maybe it was his revulsion towards his decrepit old father, and the entire magecraft establishment he stood for that would rather ravage and destroy the body of a young girl rather than accept that their days of glory were over. Maybe it was his pride, or his reluctance to show his ruined face in front of Sakura. Maybe it was just that even walking wracked his body with pain.

And maybe, mixed in with all those things, was a deep, painful shame, and a driving need to hide himself, and to be alone. Because as the worms coursed through his body and wreaked havoc on him from the inside out, they stirred up in him a disgusting, aimless lust.

He could barely think anymore. When he wasn't trying to get a few fleeting moments of rest and respite, or frantically biting and scoring his skin to distract from the agony of the worms, he was masturbating, trying to get his body calmed down, just trying to have any amount of time when he wasn't torn between physical and sexual torment. He'd become used to hurriedly jerking off in dark alleyways and public restrooms, even grinding on pipes, dumpsters, the furnishings of Fuyuki's backstreets, like a dog in heat. By this point, he might have been seen. God he tried to stay out of places where anyone might stumble upon him, but his tunnel vision was so bad most days that even if someone had yelled at him or called the police on him he wouldn't have noticed. And if the police actually had laid their hands on him, what would he have done? Probably fought them off, with the fierce wasplike adult worms, just so he could have his good hand free again.

He didn't remember doing anything like that. So it probably hadn't happened.

When his sex drive had first started picking up, not long into his training, he had been able to engage in fantasies, usually the same ones he had had in his normal life. Hot gravure models coming on to him, or, a lot of the time, Aoi. He had felt guilty about how often he thought of her like that, but assumed it was just because she was on his mind so much, because of Sakura, because of what he was doing for their family. It was alright if he rewarded and distracted himself sometimes by thinking…

But now, he didn't have anything so rational, or coherent. Most of the time, the only thoughts he could string together were a jumble of _it hurts, it hurts, I need to cum, the worms, am I alone I need to be alone make it stop make it stop—_ If he thought he could afford to let his guard down, all conscious thought would flee from him as he just concentrated on getting off as quickly and discreetly as possible. That was better than the fragmented things that came into his mind sometimes. He couldn't stand to think he had degenerated so far, and so fast, as to get hard from some of the images that floated in front of his fevered eyes. Aoi showed up a lot, yes, but so did Tokiomi, and the other masters, and a host of other incidental characters, almost anyone. He had been a normal, even bland guy once, he didn't want to admit that now he wanted to be gangbanged by drug addicts or felt up on a train or to just have his way with one of the high school girls that walked past some of his hiding places or even a cat would be fine too—he could barely remember the faces of some of the other Grail War participants, but he had an impression of some giant man that probably had an enormous cock and two beautiful white women and a lithe muscular guy with a smart mouth and some whiny greasy college kid. And there was Tokiomi whose face was etched into his mind and who Kariya was finally comfortable admitting he hated, that smarmy old-money son of a bitch who always acted like he knew what was right and always dressed to the nines and Kariya wanted him to suck him off, he wanted to force that goateed face down onto his cock and make him choke on it, he wanted to beat the shit out of him with his Berserker and make him his bitch, and then when Tokiomi was silent and used up he'd do the same to Aoi—

He hated it. He hated himself. He reveled in the throbbing pain of his old wounds in the silence after he'd finished. Thank god his salvation was brief. The restless worms and the driving need would always start up again and he'd be saved from self-loathing.

But it was in one of these periods of lucidity that something occurred to him.

He was lying on his back, partially obscured by cardboard boxes behind some restaurant that had closed down  for the night . The gravel bit into the side of his body that could still feel. The  sky that he could see through his one good eye was cloudy, with patches of bright moonlight.

Kariya closed his eye and felt the pounding of the blood in his ears slowly subside, then, after only a few minutes of calm, start to stir again. In those few minutes he might have fallen asleep. But he would never truly sleep again. The worms were always wakeful.

Why did they affect him like this? He had heard something once, maybe in his childhood or in his year-long crash course in magecraft, about the inherent magical potency of sexual acts and how they stirred up the prana or...something. There had to be techniques that used that...As if spurred on by his thinking about it, the worms stirred inside him again, and he felt the faint heat that told him he was about to be plunged into hell again. His weary mind kept wandering on some faint path about mana and its generation and its use and—something occurred to him.

He heard the voice of the man he used to be, warning him.  _Kariya. You wouldn't._

His good hand gradually inched down to his pants zipper, that he had only half done up after the last time he had zipped them down, barely half an hour ago.  _Kariya, don't._

He struggled to focus his energy in his rapidly clouding mind,  even as he started to absentmindedly stroke himself. _Kariya. You could literally fucking die._

“Berserker.”

Even before he heard the strange  guttural death rattle that the black knight made, he knew it was  listening .

“Come here.”

Summoning the black knight up was always agonizing. The worms writhed, whipped into a feeding frenzy by the merest drip of magical energy from Kariya. He gritted his teeth, tried to ride out a spasm of nerve pain that made his cock twitch.

“Come here, Berserker.”

The helmeted knight stepped forward, its posture firm and impassive, nothing of human understanding apparent in its body language. Kariya hoped that its keen battle instincts hinted at a human intelligence, or this would be like trying to fuck a dog. Or trying to get a dog to fuck you.

“Closer. Right here.”

There better be something under that armor. A dense magical fog obscured the form of the knight, making the details of its armor hard to make out, but Kariya had always assumed the armor did hide a man. Or maybe even a woman. He didn't care which anymore, especially now that the horrible possibility occurred to him that his Servant might  _be_ a suit of armor, magically endowed with a will and a taste for violence—he had to find out, and he boldly, stupidly grasped the knight by its shoulders, guiding it to kneel over him on the ground. He clumsily kicked his pants and sneakers off, and lay in the alleyway gravel baring his ruined body to the night air.

“Take this off.” He pulled at the codspiece of the knight's armor with a feeble hand. He didn't even know if it could understand him. “Here—“ He struggled to change his position on the grou nd, tried to spread his skinny legs even though one of them refused to move. His face burned at this new low he was reaching, and at how desperately he wanted to reach it. “Put it in here.” He pulled his asshole open as best he could with one hand, so there could be no mistake. “F...fuck me.”

For a few moments, Berserker did absolutely nothing. Kariya felt his temperature rise hotter and hotter, both from the embarrassment of being turned down by a dumb and unfeeling familiar, and from how badly he needed the contact, any contact.  Even then, he couldn't help but stroke himself, just a couple of times, even if he never looked away from Berserker. Maybe more than a couple of times. It just felt so good.

It actually surprised him when the armor seemed to melt away. Or maybe it didn't, but the edges of the figure seemed less hard, less angular, like the dark fog was shrouding skin instead of metal plating.  It was an eerie reminder: this was not a person. Maybe it had been once, but this was not a human being.

But it was still willing.

Kariya hastily gathered up as much saliva as he could and spit into his palm, procuring only a few pathetic gobs of spit and a couple of wayward worms. He tried to get himself wet so this bizarre encounter wouldn't be quite as painful, but most of the makeshift lube ran down his shaking arm before it got anywhere near his ass. He cursed behind clenched teeth and prepared to make another attempt.

Berserker was impatient, or didn't understand what he was doing. It grabbed him by the legs and pulled him up against itself, dragging him through the dirt. Kariya felt hands on him, and the warmth of body heat, but he could barely see Berserker through the dark and the fog. That's okay, he didn't need to see. Here it was, physical contact, sex. He didn't care who it was with or what they did to him.

The black knight was grinding on him, against his hard cock and his good leg and maybe his bad leg too. It had a dick. It felt like a big one. Kariya felt his mouth watering even as his leg shook. Was it going to hurt? It was probably going to hurt. He didn't care.

“Fuck me,” he begged, trying his best to grind against it in turn, to keep his legs spread open. “Please. Come on. Fuck me.” He didn't know what the hell he was saying, phrases that sounded like they had come from porn, barely even loud enough to hear, or was he even saying them or just thinking them? And could Berserker hear it anyway? He didn't know, but he tried to grab at the knight's cock, to try to guide it or help jerk it off or something. The knight batted his hand away.

Instead it grabbed Kariya and turned him onto his side, his good side, and forced him open with—its hands? Not its hands, something else. What did it have that wasn't hands? Then it jammed itself in, roughly, all at once. Kariya rasped a silent cry, then made another sound that could have come from a stray cat. The worms squirmed in a feeding frenzy, jerking his body around, contorting his shape. Kariya felt like he was nothing but the dirt they crawled in. This wasn't two people fucking, this was an orgy.

Berserker fucked like it was trying to kill him, hard and fast. And yet for some reason, Kariya was so sensitive that he was going out of his mind with pleasure. He heard fast little noises that were somewhere between a man sobbing in pain and the squeaks of a lost baby animal—that was him. He thought for a fraction of a second that he should feel ashamed of himself, but the next second he had forgotten to. Berserker thoughtlessly rubbed his face in the gravel and the dirt, and it was wet with Kariya's drool. He couldn't see. His good eye was glazed over and filled with tears. It was so good, it felt so good, it felt like he was almost approaching relief. He heard himself thanking Berserker over and over and telling it he loved it and just whisper-repeating its name.

And then it left him.

Kariya opened his mouth to protest but all he got was a faceful of dirt as he was turned over and entered again, fully from behind. He felt the warmth of the Servant's body on his back and more than ever, he could hear its wild breathing, like a bull or a stallion about to charge. It rutted into him, forcing his face into the ground with one hand and using the other to pull Kariya's hips closer, so he had no chance of escape. Kariya felt like he was made of jello—or worms. Had he cum already? Was he going to cum again? His leg was shaking so hard that if Berserker hadn't been holding him close he would have collapsed. He tried to cry and whine, but realized that at some point he had started biting his dead arm hard enough to draw blood.

Berserker used him relentlessly, emotionlessly, and eventually Kariya's voice went dry. There was no use vocalizing to something that wouldn't even care if he were alive or dead, that would keep fucking him even if it killed him. By the time the black knight came, spilling its seed so deep into Kariya he couldn't feel it, it could have been minutes or hours.

Kariya lay in the dirt, his eye intent on studying and mapping one single chunk of gravel, because it was there. His ass was raw, and he could already feel new bruises forming where the knight had gripped him and where he had been pressed into the ground. His breath came in quick, harsh, too-shallow gasps.

The worms were calm.

Kariya was too exhausted to move, even to put his pants on, even to close his legs. After a while, he felt something warm creep out of him, cum or maybe blood or some other unknown fluid his body could produce now. A shudder went through him.

_I hope you're proud of yourself. Did you like that?_ He heard his own voice echo in his empty head.

He closed his eye. The air was chilly on his skin.

He fell asleep before he could answer, and he didn't dream.


End file.
